Option 1) Byproducts. Say something has H2SO4 as a byproduct. That water is no longer drinkable. It is now Sulfuric Acid.(Sulfuric Acid is actually usually a "product" not "byproduct" but I can't think of a "useless" substance at the minute).

Option 2) Products. We use the water in making something. It could be something drinkable (any soft drink), or it could be just anything liquid (sulfuric acid).